Automatic telephone-exchange system for subscribers&#39; lines with extension sets.



F. ALDBNDORFF. ANGE SYSTEM FOR SUBSGRIBBRS LINES WITH EXTENSION SETS.

APPLICATION IILBD SEPT. 4, 1913.

AUTOMATIC TELEPHONE EXGH Patented Mar. 9, 1915.

2 SHEETB-SHEET 1 Fig.2

%BM1 Q W/fnesses: QM M I 1?. ALDENDORFF. ANGE SYSTEM EOE SUBSORIBBRS LINES WITH EXTENSION SETS.

APPLICATION FILED SEPT. 4, 1913.

AUTOMATIC TELEPHONE Exc Patented Mar. 9, 1915.

2 SEEBTSSHEET z.

l V/fnesses:

FRITZ ALDENDORFF, 0F ANTWERP, BEL COMPANY, OF NEW YORK, N. Y

GIUM, ASSIGNOR TO WESTERN ELECTRIC A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE-EXCHAN GE SYSTEM FOR SUBSCRIBERS LINES WITH EXTENSION SETS.

Application filed September T all whom it may concern Be it known that I, FRITZ ALDENDORFF, a subject of the King of Great Britain, residing at 59 Rue Wouw, Mortsel, Antwerp, Belgium, have invented an Automatic TelephoneExchange System for Subscribers Lines with Extension Sets, of which the following is a true, clear, concise, and exact description.

My invention relates to automatic telephone systems and has to do more particularly with such systems connected to private telephone installations having an attendants station at which the connections with ex-- tension stations are established.

The object of the invention is to provide circuits for the final selectors and the private installation by means of which the attendant at the private installation can, after he has ture of the microphonic been called,'inquire the wishes of the calling subscriber, and then extend the connection to the wanted extension and replace his re ceiver without causing the selectors at the exchange to be restored to their normal condition as would be the case with the circuits generally known at the present time.

The release of the selectors of an auto matic exchange with common battery working is effected in the known systems by a relay at the exchange responding to the ruptransmitter supply current on the replacement of the receiver. In circuits of this kind the at'tendants station in a private installation would, after he has inquired the wishes of the caller and made the connection'With-the desired extension, cause the selectors at the exchange to be restored to their normal condition if he did not wait until the called extension had responded to the'call and thus closed the microphonic supply circuit. From this it appears that if stepping relays or special stepping switching devices are not to be used at the final selector, which would permit of several openings and closings of the wanted line circuit before releasing, a release'circuit must be provided which is quite independent of the microphonic supply circuit. According to the invention this object is attained by providing release circuits at the final selector and at the private installation which only respond toa momentary earthing of one or the other or both of the line limbs. The momentary earthing of one or the other Specification of Letters Patent.

Patented Mar. a, 19115.

4, 1913. Serial No. 788,146.

or both of the line limbs is effected by the hook switch at the attendants station on the replacement of the receiver. The device which is provided on the attendants station for connecting the extension sets to the telephone line is so arranged that the earth c0nnection of the hook switch, which is used in order to eflect the release, is broken whenever the attendant makes a connection with an extension set. In an installation of this kind it may happen that the extension set connected to by the attendant does not respond to the call, so that the selectors of the exchange would be permanently held in their operative position. In order to prevent this contingency arising, a timed contact device is provided which, after a certain time has elapsed, effects the momentary earthing of the telephone line that is used for releasing the selectors. This timed contact device is controlled by an electromagnet which stops the action of the timed contact the moment the called extension set responds, so that after the response of the extension set the release of the selectors is controlled entirely by the extension station. The said electromagnet is preferably arranged to actuate a signal which informs the attendant as to whether a conversation is being carried on with an extension set or not. The clectromagnet can also be used for releasing the connection between the extension set and the exchange line.

The invention is shown in the accompanying drawing.

Figure 1 shows the circuits of the special release relay R R Fig. 2 shows another way of connecting this relay. Fig. 3 represents the mechanical arrangement of the parts at the private installations. The invention has only to do with the elements of the final selector of the automatic exchange that are concerned in the release of. the selector and with the devices of the private installation. clearness only these elements are shown.

In Fig. 1 20,20 represent the movable talking contact arms, is, is, the fixed bank contacts of the final selector. bank contacts of the selector, line, 1, 2, leading to the private installation is connected. Rs represents a relay which afterthe final selector has established the For the sake of simplicity and To each pair of the an exchange When the receiver of is off the hook current battery B through the relay Rs, winding R armature at, contact arm w, line limb 1, hook switch it, contact 3, winding of the induction coil 6, microphonic transmitter m, line limb 2, contact contact arm u armature 5, relay winding R, retardation coil D, to the other pole of the battery B. The windings t, R are both on the same relay and act differentially so that the current above described that flows through the two line limbs in series does not affect the armature 8of thedilferential relay, but when the receiver at the attendantfs station is replaced on the switch hook h, the one line limb 1 is momentarily connected by the hook switch contact 10 with the earthed contact 9 and the lower relay winding is v.shortcircuited so that the neutralizing effect of the lower coil is destroyed and the upper coil causes the armature to be attracted so as to close the circuit of the release magnet RM It is to be noted that the contact 9, 10, of the hook switch 72. is arranged in the well known manner so as to close the contact 9, 10 only on'tlie receiver being replaced on the hook but not when-the switch hook rises on the receiver being taken off. If the attendant after he has responded to a call finds that aconnection with an extension, for instance E is desired, he depresses a button B and thereby closes the contacts the switch hook by opening the On the attendant now replacing his receiver, the momentary earthing of the subscribers line does not take place and the selectors at the exchange are not released. The releasing of' the selectors upon the termination of conversation is then performed by the called extension. Upon returning the switch hook to normal, it m0- mentarily engages a grounded contact which contact 9 of contact 11.

connects conductor 1 of the line to earth in the same way as this is effected by the attendants set on the receiver being replaced on the switch hook. tension fail to respond a timed contact TO, the spring of which is tensioned on the button B 'being depressed, will earth the one limb of the subscribers line after a certain time has elapsed and thus cause the release relay R B, to energize and release the selectors. If they extension set responds before the timed contact has been moved sutficalled line.

by the. actuation of a relay Rs.

13*, the electroniagnet Rt 12, 14:, and at the same time .removes the earthed connection 6 from the.

Should the exciently to earth the line, the winding RT which is included in series with said set receives current and attracts the armature 15 which has the effect of arresting the escapement cl by a stop 16; so as to stop the motion of the time contact TC and to prevent this contact from earthing the line limb 1 and effecting the release. On the receiver being replaced by the extension set E} the momentary earthing of the subscribers line causes the release of the selectors at the exchange in the manner already described. In addition to this the interruption of the current through the winding Rt causes a signal to be displayed to the attendant signifying that the exchange free, and the button B is released and in addition the catch 16 goes mal position.

In Fig. 2 the coils of the release relay RR are connected in bridge, instead of in series to ithe line limbs as shown in Fig. 1. The working of this circuit is substantially the same as that of Fig. 1.

Fig. 3 shows the mechanical arrangement of the keys B B Fig. 1 the timed contact TO, the releasing mechanism of the keys B which actuates said releasing mechanism, and of the signal that intimates to the attendant at M whether the exchange line is being used by an extension set. The keys B, B each havea shaft 19, which is capable of sliding up and down in a hole in a plate 18. The keys are maintained in their raised positions by springs 20. At the end of each shaft there is a cone 21 which, on the particular key being depressed operates the contacts 11, 12, 11, Fig. 1. Each shaft has also another cone 22, which engages with a locking plate '23. This locking plate is kept pressed against the cones 22 by a spring 24 bearing against the projection 25, the locking plate being arranged to revolve about a shaft 2-8. On a key 13, B", etc., being depressed, the locking plate 23 is moved outwardly from the 19 and presses against the bent end 27 of a lever 28, which moves about a pivot 29 and has a toothed sector 30 at itslower end. The depression of the button and the ensuing outward mo'vement of the locking plate 23 has the effect of moving the sector 30 inwardly so as to cause a wheel 31 to revolve upon a pivot 32 in the direction indicated by an arrow. This movement of the sector 30 has the effect of tensioning a spring 44 and when the bent upper portion33 of the locking plate slides over the upper end of the cone 22 ofv the depressed key the spring 44 will exert a pull upon the sector 30 and will turn thewheel 31 toward its normal position. Attached to the wheel 31 is the contact TC. The movable contact TO brushes past fixed contact- 17. In moving,

away from its normal position, aninsulated line has become shaft surface 3-1 of the time contact TC will brush past the fixed contact 17, but when the wheel 31 is moved toward its normal position by the tension of the spring 14, the lower surface of the contact TC will brush past the fixed contact 17 and make contact just before the wheel 31 reaches its normal position. If the extension set corresponding to the depressed buttonfor instance B responds to the call within a reasonable time, the energization of the magnet Rt will cause the attraction of the armature l5 and bring a catch 16 into the path of an extension 35 attached to an escapement cl, which controls the movement of the wheel 31. Thus when the extension set responds to the call, the catch 16 will prevent the further movement of the wheel 31 into its normal position and will thereby prevent contact being made between TC and 17. During the attraction of the armature 15 a target 36 will become visible behind an opening 37 at the attendants station M, and this willintimate to the attendant that the extension set has responded and is using the exchange line. lVhen the armature 15 is attracted by the magnet Rt a pin 38 brushes past an extension 39 attached to a spring 40 and tends to push the locking plate 23 more firmly against the cone 22. The spring 39 gives way slightly to the pressure of the pin 38 when the armature 15 is pulled downward,

but when the magnet Rt is deenergized and the armature 15 is pulled back into its normal position by a spring 41, the other side of the pin 38 brushes against the extension 39 and the lower end of the spring 40 now butts against an extension 42 attached to the plate 23, and does not give way to the pressure of the pin 38 but moves the locking plate 23 outwardly and releases the depressed key for instance B, which is now pushed upward into its normal position by the spring 20. In case the extension set does not respond within a v nection has been made by the attendant, the electromagnet Rt which is in series with the upper winding R will be momentarily energized when the contact TC brushes against the fixed contact 17 on the return movement of the wheel 31. This momentary energization of the electromagnet Rt will cause the oscillation of the armature 15 and thus will cause the oblique plate 38 to move the looking plate 23 and release the depressed key, for instance B In order to prevent the escapement d from being arrested by the catch 16 whencontact is made between TC and 17, a suitable projection 43 is fixed to the wheel 31, which pushes the catch 16 out of the range of the; extension 35 of the escapen'ient I]. Thus the catch 16 willonly become effective if the contact TC has been moved beyond fixed contacts 17 loy the depression of a key 13, B etc.

.tendants station reasonable time after con-- cuit being controllable at I claim 1. In a telephone exchange system in which connections are established by selector switches, telephone stations each comprising an attendants station and an extension station, a special selector releasing circuit extending to each said attendants station and controllable at this station, and means for transferring the control of the said special selector releasing circuit to the said extension station prior to the response of the subscriber at said station.

2. In a telephone exchange system in which the connections are established by selector switches, telephone stations each comprising an attendants station and a plurality of extension stations, a special selector releasing circuit extending to each atand controllable at this station, and means for transferring the control of the said special selector releasing circuit to any of the said plurality of extension stations prior to the response of the subscriber at said station.

3. In a telephone exchange system in which the connections are established by selector switches, telephone stations each comprising an attendants station and an extension station, a microphonic battery supply circuit extending from the said exchange system to a said attendants station, a special selector releasing circuit extending to each said attendants station and controllable at this station, means for transferring the control of the special selector releasing circuit to a said extension station.

4. In a telephone exchange system in which the connections are established by selector switches, telephone stations each comprising an attendants station and an extension station, a microphonic battery supply circuit extending from the said exchange system to a .said attendants station, a special selector releasing circuit formed of a part of the said microphonic battery supply circuit said special selector releasing circuit being controllable at a said attendants station, means for transferring the control of the said special selector releasing circuit to a said extension station.

5. In a telephone exchange system in which the connections are established by selector switches, telephone stations each comprising an attendants station and a plurality of extension stations, a two-position switch at each said attendants station, a conductor connected to each of the said twoposition switches to a contact at a point between the two positions of the said twoposition switch, a special selector releasing ,circuit extending to each said attendants station and including the said conductor which is connected to the said two-position switch, said special selectonreleasing cirthe said attendants cuit a certain time station, means for opening the said conductor connected to the said two-position switch and for transferring the control of the said special selector releasing circuit to a said extension station.

6. In a telephone exchange system in which the connections are established by selector switches, telephone stations each comprising an attendants station and an extension station, a microphonic batterysupplycircuit extending from the said exchange system to a said attendants station, a line extending from the said attendants station to its extension station, a two-position switch at the attendants station which controls the said microphonic battery supply circuit, a switch for connecting the said microphonic battery supply circuit to the said extension line, a conductor the said two-position switchand to the said extension switch, a special selector releasing v circuit extending to each attendants station and including the said conductor which is connected to the two-position switch and the extension switch, contacts on the said extension switch for connecting the said microphonic battery supply circuit to the said extension line and for opening the saidspecial selector releasing circuit.

7. in a telephone exchange system in which the connections are established by selector switches, telephone stations each comprising an attendants station and a plurality of extension stations, a special selector releasing circuit extending to each attendants station and controllable at this station, means for transferring the control of the said special selector releasing circuit to any of the said plurality of extension stations, a timed contact, means for actuating the timed contact which causes it to close the special selector releasing cirafter the actuation of the means for transferring the control of the said special selector releasing circuit.

8. In a telephone exchange system in which the connections are established by selector switches, telephone stations each com-' prising an attenda'nts station and an extension station, a special selector releasing circuit extending to each attendants station and controllable at this station, means for transferring the control of the said special selector releasing circuit to a said extension station, a timed contact, means for actuating the timed contact which causes it to close the said special selector releasing circuit a certain time after the actuation of the means for transferring the control of circuit.

0. In a telephone exchange system in 'which the connections are established by selector switches, telephone comprising an attendants station and an means for transferring connected to the said special selector releasing stations each extension station, a special selector releasing circuit extending to each attendants station and controllable at this station, the control of the said special selector releasing circuit to a said extension station, a timed contact, means for actuating the timed contact that causes it to close the said special selector releasing circuit a certain time after the actuation of the means for transferring the control of the said special selector releasing circuit, an electromagnet for stopping the action of the said timed contact, said electromagnet being controlled by a said extension station.

10. In a telephone exchange system in which the connections are established by selector switches, means for restoring said switches, telephone station's each comprising an attendants station and an extension station, a microphonic battery supply circuit leading from the said attendants station to a said extension station, means for connecting the said microphonic battery supply circuit to the said extension line, a spec1alre leasing circuit leading to a said attendants station and formed of a part of a said microphonic battery supply circuit the said special releasing circuit being extended to the said extension line by the said means for connecting the said microphonic battery supply circuit to the said extension line, said restoring means being actuated only upon the closure of the said releasing circuit. I

11. In a telephone exchange system in which the eonnectionsare established by selector switches, telephone stations each comprising an attendants station and a plurality of extension stations, a microphonic battery supply circuit leading from the said selector switches to a said attendants station, a special selector releasing circuit formed of part of such microphonic battery supply circuit and including a two -'position switch at the said attcndants station which is normally held in the one position, and a conductor eonnccted to the said two-position switch, said special release circuit being capable of in g closed when the said two-position switch is moved into the said one position, means for opening-said conductor and for extending the special releasing circuit to any one of the said extension stations;

12. In a telephone exchange system in which the connections are established by selector switches, telephone stations each com-' prising an attendants station and an exten sion station, a microphonic battery supply circuit leading from the said selector switches to a said att'endauts station, a special releasing circuit for the said selector switches formed of a part of a said microphonic battery supply circuit, a switch at 13 cuit for the 'lector switches,

the attendants station .forcontrolling the said release circuit, means for transferring the control of the said releasing circuit from the said switch to the said extension station, and a timed contact for closing the said special releasing circuit.

13. In a telephone exchange system in which the connections are established by selector switches, telephone stationseach comprising an attendants station and an extension station, a main line leading from the said selector switches to a said attendants station, an extension line leading from the attendants station to the extension station, a

lockable switch for connecting the main line to the extension line, a release circuit for the said selector switches, an electromagnet included in the said release circuit for unlocking the said lockable switch.

14;. In a telephone exchange system in which the connections are established by setelephone stations each comprising an attendants station and an extension station, a main line leading from the said selector switches to a said attendants station, an extension line leading from the said attendants station to the extension station belonging thereto, an extension switch for connecting the said main line to the extension line, a lockingdevice for locking the said extension switch, a releasing cirsaid selector switches, a timed contact for closing the said releasing circuit, an electromagnet for unlocking the said extension switch and for arresting the action of the said timed contact.

'15. In a telephone exchange system in which the connections are established by selector switches, telephone stations each comprising an attendants station and an extension station, a main line leading from the said selector switches to the said attendants station, an extension line leading from the attendants station to the extension station, an extension switch for connecting the said main line to the extension line, a locking device for locking the said extension switch, a releasing circuit for the said selector switches, a timed contact for closing the said releasing circuit, a signal at the attendants station, an electromagnet for unlocking the said extension switch for arresting the action of the said timed contact and for displaying the said signal. 16. In a telephone which the connections are established by selector switches, telephone stations each comprising an' attendants station and an exten sion station, a main line leading from the said selector switches to the said attendants station, an extension line leading from the attendants station to the extension station, an extension switch for connecting the said main line to the extension line, a locking deexchange system in Vice for locking the said extension switch, 7

a releasing circuit for the said selector switches, a timed contact for closing the said releasing circuit, a signal at the attendants station, an electromagnet included in the said releasing circuit said electromagnet operating to unlock the said extension switch to arrest the action of the said timed contact and to display the said signal.

In witness whereof, I hereunto subscribe my name this 14th day ofAugust, A. D.

FRITZ ALDENDORFF. Witnesses G. DE LERRY, H. TUCK SHERMAN. 

